The passenger's velocity is indeterminate from the information given (no direction).
The passenger's speed relative to the ground is
The train is moving at a speed relative to the ground
The passenger is moving at a speed relative to the train
To calculate the relative speed of the passenger to the ground,
But here the direction of travel for the passenger is opposite that of the train, so his speed becomes a negative value.
If the train were to be travelling north at this moment, the passenger would be travelling at a